1. Field of the Invention
The present invention relates to a dual-mode sheet sorting apparatus for sorting the sheets emitted from a copier or a duplicator, and more particularly to a sheet sorting apparatus provided with a first mode sheet storage section for ordinary sheet sorting and a second mode sheet storage section capable of automatic sheet sorting in preference to the first mode operation when necessitated or after the completion of operation in the first mode.
2. Description of the Prior Art
The conventional sheet sorting apparatus have been designed to sort, page after page, the sheets emitted from a copier or a duplicator into suitable sorting trays, but the recent image forming apparatus such as copiers designed for a higher speed and a higher working efficiency are now provided with multiple functions, including so-called "cut-in" and "reservation" functions, to which the sorting apparatus are also required to respond.
The "cut-in" is a function to enable the copier to interrupt the copying operation in case of an urgent need for another copying and to restart the interrupted copying operation after the completion of a desired number of urgent copies.
Also, the "reservation" is a function to enter, during a copying operation with an automatic original feeder, the copying conditions of a next user, thereby automatically conducting, upon completion of said copying operation, the copying operation for said next user.
However, such cut-in function performed in a conventional apparatus often results in the mixing-up of the copy sheets for such urgent copying with those of the interrupted copying operation. Particularly in case a sheet sorting apparatus is in use, the sheets for such urgent copying are mixed into the sheets already sorted, and for this reason it has been necessary in the cut-in function to manually extract such mixed sheets from the sorting apparatus or to insert suitable markers such as colored sheets in advance of the urgent copy function.
Also in the reservation function, because of the similar inconvenience, the next user has to wait until the completion of the preceding copying operation.
Already there is known, as disclosed in the Japanese Utility Model Publication No. Sho53-7765, a sorting apparatus in which the sorted sheets are displaced by a pushing mechanism from a storage position to a take-out position, but such mechanism is not suitable for a copier provided with the cut-in function and hence does not solve the above-mentioned inconvenience since the sheets, once displaced by said pushing mechanism at the interruption of the copying operation, cannot be returned to the original storage position.